Abstract

Using near-field optical beam induced current, we spatially resolve the photocurrent in polycrystallinesolar cells, and observe increased photocurrent collection at grain boundaries (relative to the intragrain volume). This observation supports previously reported hypotheses that grain boundaries present a hole-barrier, thereby assisting in charge separation at the grain boundaries in these devices. The results offer compelling evidence, in an actual working-device structure, of the role of grain boundaries in explaining the surprisingly high performance of these highly defected devices.

Received 29 June 2004Accepted 25 August 2004Published online 29 October 2004

Acknowledgments:

This work was funded by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Solar Energy Technologies Program, under Contract No. DE-AC36–99GO10337 to NREL. The authors would like to acknowledge A. Duda for assistance with photolithography.